How to fix your network when you see ‘Another device is using your IP address’ on a Mac

Internet networking involves a lot of alchemy, and I confess to occasionally dropping an eye of newt (or an IP of newt) into a boiling pot to fix problems on my local network. There’s a particular message that macOS displays in limited cases that is perplexing because it’s the sort of low-level bubbling up that Apple generally takes care of. In this case, your Mac alerts you to a problem that may be of your making or might involve your Wi-Fi gateway or broadband modem.

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